Poland’s Undersecretary of State for Defence Tomasz Szatkowski said the deployment was necessary because of Russia’s “large exercises” next to its border and its “aggressive actions in our vicinity – I mean Ukraine and the illegal annexation of Crimea”.

Trump factor

More than 80 main battle tanks and hundreds of armoured vehicles have already arrived in Germany and are now being moved into eastern Europe by road and rail.

Image copyrightAFPImage captionThe plan is to rotate the forces every nine months

Part of the US force entered at Poland’s Olszyna border crossing with Germany on Thursday.

The plan is to rotate the forces every nine months. Other nations involved in the rotation are Estonia, Latvia, Lithuania, Romania, Bulgaria and Hungary.

The US Armoured Brigade will also carry out military exercises in the Baltics, all part of President Obama’s response to Russia’s intervention in Ukraine and to reassure nervous Nato allies.